[Plurihormonal PIT1-lineage pituitary neuroendocrine tumors: a clinicopathological study]

Objective: To investigate the clinicopathological characteristics of plurihormonal PIT1-lineage pituitary neuroendocrine tumors. Methods: Forty-eight plurihormonal PIT1-lineage tumors were collected between January 2018 and April 2022 from the pathological database of Sanbo Brain Hospital, Capital Medical University. The related clinical and imaging data were retrieved. H&E, immunohistochemical and special stains were performed. Results: Out of the 48 plurihormonal PIT1-lineage tumors included, 13 cases were mature PIT1-lineage tumors and 35 cases were immature PIT1-lineage tumors. There were some obvious clinicopathological differences between the two groups. Clinically, the mature plurihormonal PIT1-lineage tumor mostly had endocrine symptoms due to increased hormone production, while a small number of immature PIT1-lineage tumors had endocrine symptoms accompanied by low-level increased serum pituitary hormone; patients with the immature PIT1-lineage tumors were younger than the mature PIT1-lineage tumors; the immature PIT1-lineage tumors were larger in size and more likely invasive in imaging. Histopathologically, the mature PIT1-lineage tumors were composed of large eosinophilic cells with high proportion of growth hormone expression, while the immature PIT1-lineage tumors consisted of chromophobe cells with a relatively higher expression of prolactin; the mature PIT1-lineage tumors had consistently diffuse cytoplasmic positive staining for keratin, while the immature PIT1-lineage tumors had various expression for keratin; the immature PIT1-lineage tumors showed more mitotic figures and higher Ki-67 proliferation index; in addition, 25.0% (12/48) of PIT1-positive plurihormonal tumors showed abnormal positive staining for gonadotropin hormones. There was no significant difference in the progression-free survival between the two groups (P=0.648) by Kaplan-Meier analysis. Conclusions: Plurihormonal PIT1-lineage tumor belongs to a rare type of PIT1-lineage pituitary neuroendocrine tumors, most of which are of immature lineage. Clinically increased symptoms owing to pituitary hormone secretion, histopathologically increased number of eosinophilic tumor cells with high proportion of growth hormone expression, diffusely cytoplasmic keratin staining and low proliferative activity can help differentiate the mature plurihormonal PIT1-lineage tumors from the immature PIT1-lineage tumors. The immature PIT1-lineage tumors have more complicated clinicopathological characteristics.

[Clinicopathological characteristics of H3K27-altered diffuse midline glioma and evaluation of NTRK as its therapeutic target]

Objective: To investigate the clinicopathological characteristics of H3K27-altered diffuse midline glioma (DMG), and to analyze DMG's prognostic factors, and subsequently, to study the possibility of using NTRK as a therapeutic target for DMG. Methods: A total of 232 DMG diagnosed at the Sanbo Brain Hospital, Capital Medical University, Beijing, China from July 2016 to March 2021 were collected. Their clinical, radiological and pathological features, the ratio of MGMT promoter methylation, expression of NTRK, and characteristics of NTRK gene fusion were analyzed. The prognostic values of different factors were also studied, including age, tumor location, histological grade, gene and protein expression of NTRK, and postoperative adjuvant therapy. Results: Among the 232 DMG cases, there were 8 patients with both primary and relapse tumors on the record. Thus, a total of 224 patients were analyzed, including 118 males and 106 females. There were 126 adults (>18 years of age) and 98 children (≤18 years of age). Notably, the most frequent location was thalamus (41/126, 32.5%) in adults, but brainstem (59/96, 60.2%) in children. The lesions showed T1 hypointensity or isointensity, and T2 hyperintensity. However, contrast enhancement patterns of the tumors varied, with many tumors lacking contrast-enhancing. The histological grades included grade 2 (9/224, 4.0%), grade 3 (41/224, 18.3%) and grade 4 (174/224, 77.7%). Two hundred and twenty-four DMGs were diffusely positive for H3K27M and negative for H3K27me3. The ratio of MGMT promoter methylation was low (1/45, 2.2%). One hundred and seventy-seven of the 224 cases (177/224, 79.0%) were positive for NTRK. Fifty cases were analyzed using fluorescence in situ hybridization. Among them, five DMGs (positive rate, 10.0%) were NTRK fusion positive. This study showed that there were no differences between adult and pediatric DMGs in histological grading, expression of NTRK, and NTRK gene fusion. One hundred and fifty-nine patients were included in the follow-up analysis (P>0.05). During the follow-up period, 109/159 patients (69.6%) died of the disease, with a median survival time of 12 months (range 1 to 55 months). Univariate log-rank analysis showed that age, location, surgical procedure and postoperative adjuvant therapy were associated with overall survivals of the DMG patients (P<0.05). Conclusions: The prognosis of DMG is poor overall. There are differences between adult and pediatric DMGs in anatomic location and prognosis, but not in other features. NTRK1 gene fusion is detected in 10.0% of the tumors. It suggests that TRK inhibitor might be a choice for treating DMG.

[Pediatric SMARCB1/INI1-deficient poorly differentiated chordoma of the skull base: report of five cases and review of literature]

Objective: To investigate the clinicopathological characteristics and differential diagnosis of pediatric SMARCB1/INI1-deficient poorly differentiated chordoma (PDC) of the skull base. Methods: Five cases of SMARCB1/INI1-deficient PDC were identified in 139 cases of chordoma diagnosed in Sanbo Brain Institute, Capital Medical University, Beijing, China from March 2017 to March 2021. The clinical and imaging data of the 5 PDCs were collected. H&E and immunohistochemical staining, and DNA methylation array were used, and the relevant literatures were reviewed. Results: All 5 PDCs were located at the clivus. The average age of the patients was 6.4 years, ranging from 3 to 16 years. Three patients were female and two were male. Morphologically, in contrast with classical chordomas, they presented as epithelioid or spindle tumor cells organized in sheets or nests, with necrosis, active mitoses, and infiltration into surrounding tissue. All cases showed positivity of CKpan, EMA, vimentin and brachyury (nuclear stain), and loss of nuclear SMARCB1/INI1 expression. S-100 protein expression was not frequent (2/5). Ki-67 proliferative index was high (20%-50%). All cases had over-expressed p53. It was necessary to differentiate SMARCB1/INI1-dificient PDC from SMARCB1/INI1-dificient tumors occurring at skull base of children or the tumors with epithelial and spindle cell morphological features. The 3 PDCs with DNA methylation testing showed the methylation profiles different from the pediatric atypical teratoid/rhabdoid tumors. They formed an independent methylation profile cluster. The clinical prognosis of the 5 patients was poor, and the overall survival time was 2-17 months. Conclusions: PDC is a special subtype of chordoma, which often affects children and occurs in the clivus. The PDC shares epithelioid or spindle cell morphologic features which are different from the classic chordoma. Besides the typical immunohistochemical profile of chordoma, PDC also has loss of nuclear SMARCB1/INI1 expression and distinct epigenetic characteristics.

Third-line treatment for metastatic colorectal cancer: anlotinib is superior to chemotherapy and similar to fruquintinib or regorafenib

The clinical efficiency and adverse reactions of anlotinib in metastatic colorectal cancer (mCRC) as a third-line treatment compared with chemotherapy and regorafenib or fruquintinib was explored in this study. Clinical data from 105 mCRC patients who failed at least two lines of chemotherapy were collected. The patients were divided into three groups based on their third-line therapeutic regimen: third-line chemotherapy only (group A); anlotinib (group B); and fruquintinib or regorafenib (group C). The result showed that the ORR and DCR of group B (14.29%, 85.71%) were higher than those of group A (0%, 40.00%). The ORRs of group B and group C were 14.29% and 20.00%, respectively. Group B and group C had the same DCR, 85.71%. The mean PFS values of group B (3.46 months) and group C (3.33 months) were longer than that of group A (2.25 months) (χ2=84.255, p<0.001) and the mean PFS values of group B and group C were similar (χ2=0.884, p=0.347). The mean OS of group B was 9.22 months, which was longer than that of group A (6.95 months) (χ2=38.837, p<0.001). The mean OS values of group B (9.22 months) and group C (9.38 months) were not significantly different (χ2=0.456, p=0.499). The incidences of proteinuria, hand-foot skin reaction, myelosuppression, and gastrointestinal reaction were similar between group B and group C (p=0.173, 0.188, 1.00, 0.154, respectively). Myelosuppression and gastrointestinal reaction were more common in group A than in group B and group C (p<0.001). For mCRC, anlotinib as a third-line treatment is better than chemotherapy and similar to regorafenib or fruquintinib. The associated adverse reactions are tolerable.

[BRAF V600E mutation and clinicopathologic characteristics in 250 cases of brain tumors associated with epilepsy]

Objective: To investigate the clinicopathologic characteristics and BRAF V600E mutation of brain tumors associated with epilepsy. Methods: Totally 250 patients with brain tumors associated with epilepsy were included from March 2008 to August 2017 retrospectively at Sanbo Brain Hospital, Capital Medical University.The clinical manifestations, histological features and BRAF V600E mutation results were collected and analyzed. Results: There were 132 males and 118 females, and the male to female ratio was 1.1∶1.0. The age of patients ranged from 2 to 67 years(mean 22 years). The tumors had obvious local space occupying effect on MRI. The temporal lobe was the most common site (44.4%, 111/250). There were 58.4% (146/250) of ganglioglioma (GG), 24.0% (60/250) of dysembryoplastic neuroepithelial tumor (DNT), 12.8% (32/250) of pleomorphic xanthoastrocytoma(PXA), 4.0% (10/250) of angiocentric glioma (AG) and 0.8% (2/250) of papillary glioneuronal tumor (PGNT). Mixed GG, PXA and DNT morphological structures were found in 9 of patients. Among 250 cases, 35 cases were accompanied by focal cortical dysplasia(FCD). BRAF V600E was seen in 43 of 74 (58.1%) GG and 13 of 28 (46.4%) PXA. The most common pathologic grade of GG, DNT, AG and PGNT was WHO I. Some of the tumor cells from GG (34 cases) showed higher proliferative activity (WHO Ⅱ/Ⅲ). Most cases of PXA were WHOⅡand high proliferative activity was seen in nine cases. Conclusions: The association of low-grade glioneuronal tumors with intractable epilepsy was well-recognized. The most common low-grade glioneuronal tumors were GG.GG may occur in any part of the central nervous system, with a predilection for temporal lobe. Each type of low-grade glioneuronal tumors has its own unique histological morphology, but some may show complex features with 2 or 3 mixed components. The occurrence of BRAF V600E mutations in GG is common, and their detection may be valuable for the diagnosis and treatment in GG.

[Cognitive status and its relationship with serum neuropeptide Y in patients with obstructive sleep apnea hypopnea syndrome]

Objective:To analyze the correlation between cognitive function and serum NPY levels in OSAHS patients, and to explore biomarkers for evaluating cognitive function in adult patients with OSAHS. To verify the validity of MoCA in evaluating cognitive function in OSAHS patients.Method:72 patients with OSAHS and 16 healthy controls were included. Subjects were tested for PSG, MoCA, and MMSE; ELISA was used to detect serum NPY levels in subjects. After 14 days, 10 patients in the control group were randomly selected for re-testing of MoCA to detect the internal consistency, test-retest reliability and simultaneous validity of MoCA.Result:The cognitive dysfunction of OSAHS patients was manifested in visual spatial ability, language and attention. Serum NPY levels were negatively correlated with MoCA scores (r=-0.105), and the correlation was not significant. The internal consistency of the MoCA detected by the Cronbach coefficient α is reliable (0.690), and when "directional ability" deleted,the reliability increases (0.705); In addition, both of test-retest reliability (r=0.884, P=0.001) and simultaneous validity (r=0.701,P<0.01) of MoCA were reliable.Conclusion:MoCA in evaluating the cognitive function of adult with OSAHS is reliable, stable and effective, and when "directional ability" deleted,the reliability increases . The cognitive dysfunction of OSAHS patients is manifested in visual spatial ability, language and attention, which is obvious with the disease of severity; serum NPY levels can reflect the severity of OSAHS; there is no significant negative correlation between serum NPY level and MoCA total score. Whether it can be used to evaluate cognitive function in OSAHS patients needs further verification.

[Rare primary proximal epithelioid sarcoma in skull base: clinical analysis of four cases]

Objective: To report the clinical and pathological features of primary proximal epithelioid sarcoma (PES) in skull base. Methods: The clinical and pathological features of four cases of PES in skull base from Sanbo Brain Institute of Capital Medical University and Kunming Sanbo Brain Institute were analysed retrospectively. Results: Three cases was female, and one male, the age ranged from 46 to 52 years.All cases occurred in skull base, and sellar region was the main site of involvement.Under the microscope, the tumor cells characterized by epithelioid cell changes, with or without rhabdoid tumor cells.Mitotic figure was active.Immunohistochemical staining showed that AE1/AE3, EMA and CD34 were variously expression in tumor cells.INI-1 protein was lost in all cases.Three cases were detected by FISH, and INI1 (22q11.2) gene locus was absent in them.Three patients died less than 3 months after surgery, and case 4 was under treatment after five months of surgery. Conclusions: Primary PES in skull base mostly occurs in sellar region and its clinical prognosis is poor.It features with epithelioid/rhabdoid tumor cells with lack granuloma structure as distal ES.It has epithelial and mesenchymal differentiation characteristics.CD34 is always positive.INI1 gene deletion and protein loss expression are characteristic molecular alteration of PES.

[Neuropathologic findings in intractable epilepsy: a clinicopathologic analysis of 822 cases]

Objective: To investigate the clinicopathologic characteristics of intractable epilepsy. Methods: Based on the classification criteria proposed by the International League Against Epilepsy (ILAE), a retrospective analysis of the pathological characteristics was done in 822 patients who underwent epilepsy surgery in Sanbo Brain Hospital, Capital Medical University, from June 2008 to December 2012. Results: The mean age of epilepsy onset was 9.9 years, mean duration of epilepsy was 11.9 years. Complex partial seizures were the main presenting features. Histopathological study showed 33 cases (4.01%) with mild forms of cortical malformations, 690 cases (83.94%) with focal cortical dysplasia (FCD) and 99 cases with others (including 39 pure hippocampal sclerosis, 20 cystosclerosis, 19 Sturge-Weber syndrome, 8 tuberous sclerosis complex, 6 without significant pathological changes, 5 gyral malformations and 2 hamartoma). Among the 690 FCD cases, 106 were FCD typeⅠ, 91 were FCD typeⅡ and 493 were FCDⅢ(Ⅲa: 160, Ⅲb: 106, Ⅲc: 26 and Ⅲd: 201). Conclusions: FCDⅢd is the most common histopathological subtype causing intractable epilepsy, mainly due to focal hypoxia/ischemia in the perinatal period, which results in scarring of local brain tissue; this is followed by other isolated forms of FCD (FCDⅠand FCDⅡ), and then FCD Ⅲa and FCD Ⅲb. The reason to distinguish isolated forms of FCD (types Ⅰ and Ⅱ) from FCD Ⅲ and to subclassify FCD Ⅲ is to allow better definition of cortical dyslamination. Therefore, the pathogenic factors of intractable epilepsy can be grouped in greater details, and facilitate the diagnosis and potential curative treatment of intractable epilepsy.

[Sirt1 inhibited oxidized low-density lipoprotein induced smooth muscle cells inflammatory response]

Objective: To investigate the mechanism of inflammation of smooth muscle cells induced by oxidized low-density lipoprotein through Sirt1 in the atherosclerosis. Methods: The expression of Sirt1 had been measured in the plaque tissues of human and mice. The affection of overexpression of SIRT1 on the oxLDL induced-inflammatory response and ROS generation had been detected in this study. Results: Sirt1 decreased in smooth muscle cells region of human plaque. And in the smooth muscle cells region of mice plaque, Sirt1 was also significantly decreased about 5-fold (P<0.05). Although, oxLDL promoted inflammatory cytokines secretion and ROS generation, but this affection had been reversed by upregulating Sirt1. Conclusion: oxLDL regulated smooth muscle cells inflammatory response via Sirt1. Thus, Sirt1 is a signaling molecular regulating smooth muscles inflammatory response in the process of atherosclerosis.

Norovirus Infection and Histo-blood Group Antigens in Children Hospitalized with Diarrhea in Lulong and Chenzhou in China

Norovirus (NoV) is a pathogen that commonly causes viral diarrhea in children. Studies indicate that NoV recognizes human histo-blood group antigens (HBGAs) as cell attachment factors. In order to explore the correlation between of NoV infection and HBGAs, a cross-sectional study was conducted in children less than five years old who were hospitalized with diarrhea in two areas of China between November 2014 and February 2015. Of the paired stool and saliva samples taken from 424 children, NoV was detected in 24 (6%) children, with viral genotypes GII.3 (n=5), GII.4 (n=14), GII.12 (n=1), and GII.17 (n=4). All of the individuals having NoV infection were either secretors (Lea-b+/Lex-y+) or partial secretors (Lea+b+/Lex+y+) except one GII.3 infection of a non-secretor (Lea+b-/Lex+y-). These results suggest that secretor positive is associated with NoV infection, although non-secretors are not absolutely protected from NoV infection.

Gene Knockdown in Human Rhinovirus 1B Using 2'-OMe-modified siRNAs Results in the Reactivation of the Interferon Response

The aim of this study was to investigate the knockdown efficiency of 2'-O-methylated (2'-OMe)-modified small interfering RNAs (siRNAs) on human rhinovirus 1B (HRV1B) replication and the interferon response. Thus, 24 2'-OMe-modified siRNAs were designed to target HRV1B. The RNA levels of HRV1B, Toll-like receptor 3, melanoma differentiation-associated gene 5, retinoic acid inducible gene-I, and interferons were determined in HRV1B-infected HeLa and BEAS-2B epithelial cells transfected with 2'-OMe-modified siRNAs. The results revealed that all 2'-OMe-modified siRNAs interfered with the replication of HRV1B in a cell-specific and transfection efficiency-dependent manner. Viral activation of Toll-like receptor 3, melanoma differentiation-associated gene 5, retinoic acid inducible gene-I, and the interferon response was detected. In conclusion, the 2'-OMe-modified siRNAs used in this study could interfere with HRV1B replication, possibly leading to the reactivation of the interferon response.

Aetiology of diarrhoeal disease and evaluation of viral-bacterial coinfection in children under 5 years old in China: a matched case-control study

Globally, diarrhoeal diseases are the second leading cause of death among children under 5 years old. Few case-control studies on the aetiology of diarrhoea have been conducted in China. A case-control study on 922 children under 5 years old who presented with diarrhoea and individually matched controls was conducted in China between May 2011 and January 2013. Quantitative PCR was used to analyze stool samples for 10 diarrhoeal pathogens. Potential enteric pathogens were detected in 377 (81.8%) of 461 children with diarrhoea and 215 controls (46.6%, p <0.001). Rotavirus, norovirus GII, Shigella and adenovirus were qualitatively associated with diarrhoea. Using receiver operating characteristic curves, the optimal cutoff threshold for defining a symptomatic individual was 72, 5840, and 10(4) copies per reaction for rotavirus (odds ratio 259), norovirus GII (odds ratio 10.6) and Shigella (odds ratio 5.1). The attributable fractions were 0.18 for rotavirus, 0.08 for norovirus GII, 0.01 for Shigella and 0.04 for adenovirus. Coinfections between pathogens were common. Two pairs, rotavirus and adenovirus, and norovirus GII and Salmonella were positively associated. The co-occurrence of rotavirus and sapovirus, astrovirus, enterotoxigenic Escherichia coli or Campylobacter jejuni only occurred in children with disease. Coinfection was not correlated with clinical symptoms. Quantitative data are critical. Our results indicate that increased pathogen loads increase the OR between diarrhoea and rotavirus, norovirus GII and Shigella. Coinfections with rotavirus and norovirus GII are common and occur in a nonrandom distribution. Despite testing for ten diarrhoeal pathogens, over two-thirds of cases do not have a recognized attributable cause.

Detection of human bocavirus in children with acute respiratory tract infections in Lanzhou and Nanjing, China

OBJECTIVE

The aim of this study was to explore the prevalent characteristics of HBoV1 and its co-infection.

METHODS

PCR was used to detect HBoV1-DNA (HBoV1) and other viruses. A multivariate logistic regression model was used to explore possibility of co-detected for related viruses.

RESULTS

The positivity rates in Nanjing and Lanzhou were 9.38% (74/789) and 11.62% (161/1386), respectively (P>0.05). The HBoV1 positive group was younger than negative group (P<0.05). Seasonal differences were noted, with a higher frequency of infection in December and July. HBoV1-positive children [72.34% (169/235)] were co-infected with other respiratory viruses. Multifactorial analysis showed no correlations between HBoV1 and the clinical classification, region, gender, age, or treatment as an outpatient or in a hospital. Correlations were identified between HBoV1 infections with ADV (OR=1.53, 95% CI 1.03-2.28), RSV (OR=0.71, 95% CI 0.52-0.98), and IFVA (OR=1.77, 95% CI 1.00-3.13).

CONCLUSION

Presence of HBoV1 in nasopharyngeal aspirates did not correlate with region or gender, although the prevalence of HBoV1 was higher in younger children. There were no correlations between HBoV1 and other variables, except for the season and ADV, RSV, or IFVA infections.

Analysis of sulphonamide residues in edible animal products: A review

The methods of analysis for sulphonamide residues in edible animal products are reviewed. Sulphonamides are widely used for therapeutic and prophylactic purposes in both humans and animals, sometimes as growth promoters as additives in animal feed. As a result of their widespread use, there is concern about whether the levels used of these drugs can generate serious problems in human health, e.g., allergic or toxic reactions. Several methods for the determination of sulphonamides have been reported in the literature and this review considers high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC/MS), gas chromatography (GC), thin-layer chromatography (TLC), high-performance capillary electrophoresis (HPCE), enzyme-linked immunosorbant assay (ELISA), biosensor immunoassay (BIA) and microbiological methods. Specific aspects of analysing sulphonamides, such as sample handling, chromatographic conditions and detection methods are discussed. Methods for drug residue monitoring should be accurate, simple, economical in both time and cost, and capable of detecting residues below the maximum residue limits (MRL). The current sulphonamide detection technologies are based on chromatographic methods or bacteriological growth inhibition. The instrumental methods such as HPLC and GC are both sensitive and specific, but are laborious and expensive. Because of the labour-intensive processes, only a few cases of GC methods applied to residue analysis have been published. These methods are suitable for confirmation but not for screening of large numbers of samples. Microbiological methods do not require highly specialized and expensive equipment. They also use highly homogeneous cell populations for testing and thus result in better assay precision. Although HPCE has powerful separation ability, the precision is poor and the instrument still needs to be improved. To date, this technique has not been widely applied to routine analysis. Currently, TLC has been almost replaced by other instrumental analysis. A rapid, sensitive and specific assay is required to detect positive samples in routine analysis, which can then be confirmed for the presence of sulphonamides by HPLC. Immunochemical methods such as ELISA can be simple, rapid and cost-effective, with enough sensitivity and specificity to detect small molecules. This review can be considered as a basis for further research aimed at identifying the most efficient approaches.

Synergistic transcriptional activation of human Acyl-coenzyme A: cholesterol acyltransterase-1 gene by interferon-gamma and all-trans-retinoic acid THP-1 cells

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme involved in cellular cholesterol homeostasis and in atherosclerotic foam cell formation. Human ACAT-1 gene contains two promoters (P1 and P7), each located in a different chromosome (1 and 7) (Li, B. L., Li, X. L., Duan, Z. J., Lee, O., Lin, S., Ma, Z. M., Chang, C. C., Yang, X. Y., Park, J. P., Mohandas, T. K., Noll, W., Chan, L., and Chang, T. Y. (1999) J. Biol Chem. 274, 11060-11071). Interferon-gamma (IFN-gamma), a cytokine that exerts many pro-atherosclerotic effects in vivo, causes up-regulation of ACAT-1 mRNA in human blood monocyte-derived macrophages and macrophage-like cells but not in other cell types. To examine the molecular nature of this observation, we identified within the ACAT-1 P1 promoter a 159-base pair core region. This region contains 4 Sp1 elements and an IFN-gamma activated sequence (GAS) that overlaps with the second Sp1 element. In the monocytic cell line THP-1 cell, the combination of IFN-gamma and all-trans-retinoic acid (a known differentiation agent) enhances the ACAT-1 P1 promoter but not the P7 promoter. Additional experiments showed that all-trans-retinoic acid causes large induction of the transcription factor STAT1, while IFN-gamma causes activation of STAT1 such that it binds to the GAS/Sp1 site in the ACAT-1 P1 promoter. Our work provides a molecular mechanism to account for the effect of IFN-gamma in causing transcriptional activation of ACAT-1 in macrophage-like cells.

Analysis of the mechanism of action of non-deletion hereditary persistence of fetal hemoglobin mutants in transgenic mice

Transgenic mice carrying an (A)gamma gene construct containing a -382 5' truncation of the (A)gamma gene promoter have a phenotype of hereditary persistence of fetal hemoglobin (HPFH) but, when the CACCC box of the -382(A)gamma promoter is deleted, there is no gamma gene expression in the adult mice. We used this system to investigate the mechanism whereby human HPFH mutations result in gamma gene expression in the adult. Introduction of the -198 T-->C HPFH mutation into the CACCC-less (A)gamma gene construct re-established the HPFH phenotype, indicating that this mutation increases promoter strength, most probably by establishing a novel CACCC box sequence in the -198(A)gamma region. The HPFH phenotype was also re-established when the -117 C-->T HPFH mutation was introduced into a -141(A)gamma promoter with a destroyed CACCC box, indicating that this mutation increases gamma promoter strength in the absence of the CACCC motif. The T-->A -175 HPFH mutation failed to re-establish the HPFH phenotype when the CACCC box was deleted, indicating that gamma gene expression in this mutation is CACCC box dependent. These results provide the first in vivo experimental evidence in support of mechanistic heterogeneity of the non-deletion HPFH mutants.

Human acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) gene organization and evidence that the 4.3-kilobase ACAT-1 mRNA is produced from two different chromosomes

Acyl-CoA:cholesterol acyltransferase (ACAT) plays important roles in cellular cholesterol homeostasis. Four human ACAT-1 mRNAs (7.0, 4.3, 3.6, and 2.8 kilobases (kb)) share the same short 5'-untranslated region (exon 1) and coding sequence (exons 2-15). The 4.3-kb mRNA contains an additional 5'-untranslated region (1289 nucleotides in length; exons Xa and Xb) immediately upstream from the exon 1 sequence. One ACAT-1 genomic DNA insert covers exons 1-16 and a promoter (the P1 promoter). A separate insert covers exon Xa (1277 base pairs) and a different promoter (the P7 promoter). Gene mapping shows that exons 1-16 and the P1 promoter sequences are located in chromosome 1, while exon Xa and the P7 promoter sequence are located in chromosome 7. RNase protection assays demonstrate three different protected fragments, corresponding to the 4.3-kb mRNA and the two other mRNAs transcribed from the two promoters. These results are consistent with the interpretation that the 4.3-kb mRNA is produced from two different chromosomes, by a novel RNA recombination mechanism involving trans-splicing of two discontinuous precursor RNAs.